cp's OEIS Frontend

A376298 Numbers which are the sum of at least three successive terms of a geometric progression.

%I A376298 #12 Oct 15 2024 23:17:19
%S A376298 7,13,14,15,21,26,28,30,31,35,39,40,42,43,45,49,52,56,57,60,62,63,65,
%T A376298 70,73,75,77,78,80,84,85,86,90,91,93,98,104,105,111,112,114,117,119,
%U A376298 120,121,124,126,127,129,130,133,135,140,143,146,147,150,154,155,156,157
%N A376298 Numbers which are the sum of at least three successive terms of a geometric progression.
%C A376298 Multiples of terms in A053696.
%C A376298 Numbers of the form m*(b^n-1)/(b-1) for n > 2 and b > 1, m > 0.
%H A376298 Andrew Howroyd, <a href="/A376298/b376298.txt">Table of n, a(n) for n = 1..10000</a>
%H A376298 Wikipedia, <a href="https://en.wikipedia.org/wiki/Geometric_progression">Geometric progression</a>.
%e A376298 7 is a term because 7 = 1 + 2 + 4.
%e A376298 13 is a term because 13 = 1 + 3 + 9.
%e A376298 14 is a term because 14 = 2 + 4 + 8.
%e A376298 15 is a term because 15 = 1 + 2 + 4 + 8.
%o A376298 (PARI) B(k,lim)={vector(logint(lim*(k-1)+1,k)-2, i, (k^(i+2) - 1)/(k-1))}
%o A376298 upto(lim=200)={my(v=concat(vector(sqrtint(lim)-1, k, B(k+1,lim)))); Set(concat(vector(#v, i, my(t=v[i]); t*[1..lim\t])))}
%Y A376298 Cf. A053696, A084733, A085104.
%K A376298 nonn
%O A376298 1,1
%A A376298 _Andrew Howroyd_, Sep 19 2024